camera movement for game?
Use the mouse actuator on your camera.

delay>and>Mouse, mouse look.

Set the delay to 0.01 and enable true-level-triggering this will behave as an always sensor, but delay works better with mouse look. The delay will read 0 but it really will work for 0.01 frames.
Create a mouse actuator and set the type to mouse look.
You can specify how you want the mouse to look in the properties of the actuator. Basically, if it's turning too far when you move your mouse, increase the min. value and decrease the max. value.